/*
 *  Copyright 2013 National Institute of Advanced Industrial Science and Technology
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.sss.mapreduce.example;

import java.util.HashMap;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.sss.mapreduce.Configuration;
import org.sss.mapreduce.Mapper;
import org.sss.mapreduce.Output;
import org.sss.mapreduce.datatype.PackableInt;
import org.sss.mapreduce.datatype.PackableLong;

public class KMeansMapper extends Mapper {
  private static Logger logger = LoggerFactory.getLogger(KMeansMapper.class);
  private Center[] centers;

  @Override
  public void configure(Context context) throws Exception {
    logger.debug("configure --");
    Configuration config = context.getConfiguration();

    HashMap<?, ?> centerMap = (HashMap<?, ?>) (config
        .getObject(KMeans.CENTER_KEY));

    centers = new Center[centerMap.size()];
    for (int i = 0; i < centers.length; i++) {
      centers[i] = (Center) centerMap.get(i);
    }
  }

  public void map(Context context,
                  PackableLong key, KMeansPoint value,
                  Output<PackableInt, Center> output)
      throws Exception {
    double x = value.x;
    double y = value.y;
        
    // logger.debug("here");
    int index = -1;
    double minDist = Double.MAX_VALUE;
    for (int i = 0; i < centers.length; i++) {
      double dist = centers[i].distance(x, y);
      if (dist < minDist) {
        minDist = dist;
        index = i;
      }
    }
    output.write(new PackableInt(index), new Center(x, y));
  }
}
